Antithyroid-antibody activity in the snyovial fluid of patients with various arthritides.

Microsomal and thyroglobulin autoantibody activity has been detected in synovial fluid from 34 of 50 patients with various arthritides (rheumatoid arthritis, ankylosing spondylitis, osteoarthrosis, and gout). Serum from only 4 of these patients showed thyroid-autoantibody activity, and the serum titres were considerably lower than the synovial-fluid titres. This suggests that thyroid autoantibody is produced locally in the joints of these patients.